High Altitude May Give Rise to IBD Flares

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These studies were published as abstracts and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.

Traveling at high altitudes -- be it a mountain vacation or an hour-long flight -- may put irritable bowel disease (IDB) patients at risk for flares.

Point out that in another study, oxygen deprivation triggered the repression of transcription of solute carrier transporter genes, which can impact intestinal absorption.

SAN DIEGO -- Traveling at high altitudes -- be it a mountain vacation or an hour-long flight -- may put inflammatory bowel disease (IDB) patients at risk for flares, researchers reported here.

Travel at heights of at least 2,000 meters (about 6,562 feet) above sea level triggered IBD flares in patients within 4 weeks of being at the altitude, according to data presented by Stephan Vavricka, PD, of Trieml Hospital in Zurich, and colleagues here at Digestive Disease Week.

There has been early evidence that hypoxia can induce inflammation in the gastrointestinal tract, but the clinical impact of hypoxia in patients with IBD has not been thoroughly investigated, the authors explained.

Vavricka participated in two studies on IBD and hypoxia: The first looked at whether flights and/or high altitude were risk factors for IDB flares. The second study evaluated the influence of hypoxia in high altitudes on the expression levels of solute carrier transporters in the intestines.

For the first study, Vavricka and colleagues issued questionnaires to 103 IBD patients presenting at three Swiss IBD clinics with an IBD flare between September 2009 and August 2010. They were asked about their habits 4 weeks prior to the flare.

Patient responses were divided into two groups: 52 patients with flare and 51 without (remission). Patients in each group were matched according to age, gender, smoking habits, and medication used in the 4 weeks prior.

Among 103 patients, 43 had Crohn's disease and 60 had ulcerative colitis. The majority of patients with both conditions were female and were similar in age: 39.3 for those with Crohn's disease and 43.1 for those with ulcerative colitis.

IBD patients with flares reported traveling to heights of at least 2,000 meters during the study period more frequently compared with patients in remission (40.4% versus 15.7%, P=0.005), Vavricka reported.

Additionally, a significant number of patients with Crohn's disease reported having a flare and had traveled at high altitudes versus Crohn's disease patients without flares (38.1% versus 9.1%, P=0.024).

There was also a trend for more frequent high-altitude travel in patients with ulcerative colitis than in patients with no flare (41.9% versus 20.7%, P=0.077).

Patients who had experienced flares after being at higher elevations spent anywhere from 1 to 2 hours flying to an extended, week-long holiday in the mountains, Vavricka said at a DDW press conference. The mean flight duration was 5.8 hours.

The authors concluded that flights and staying at high altitudes were risk factors for IBD flares but noted that a large, prospective study was required to confirm their results.

He added that future research could also look into the molecular biology of viscera to see microbe response to higher elevation, particularly in deoxygenated settings, like mountains versus airplanes, which presumably have oxygenated cabins.

In the second study, the authors performed duodenal biopsies in people exposed to high altitude hypoxia and compared them with biopsies taken prior to altitude exposure. They found that biopsy samples from exposed individuals expressed significantly lower levels of nucleoside transporters CNT1 (P<0.0001) and CNT2 (P=0.0037).

Additionally, levels of several transporters, including serotonin, were significantly lower in the hypoxic duodenums (P=0.02).

They concluded that oxygen deprivation triggered the repression of transcription of solute carrier transporter genes, which can impact intestinal absorption.

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